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Histamine in Fish and Fishery Products

Who is this FAQ intended for? 
This information is intended for food business operators, enforcement officers and other interested parties. It:

  • Provides information on the causes of histamine food poisoning linked to fish and fishery products
  • Includes the relevant legislation governing acceptable limits of histamine in fish and fishery products
  • Provides information on how to minimise the risk of histamine build-up in fish and fishery products

What is histamine? 
Histamine is a biogenic amine which is a naturally occurring substance in the human body. Histamine is derived from the breakdown (decarboxylation) of the amino acid histidine. It has important physiological functions related to local immune responses, gastric acid secretion and neuromodulation. Histamine is involved in the body’s inflammation response and, if elevated levels are ingested, it can produce symptoms similar to that of an allergic reaction.

What is histamine food poisoning? 
Histamine or “Scombroid fish” poisoning is a foodborne illness most commonly caused by consuming certain species of marine fish (e.g. tuna, herring, mackerel) that have naturally high levels of histamine and possibly other biogenic amines in their tissues. After fish, cheeses are the foods most commonly associated with histamine poisoning. However, histamine production can occur in other foods such as fermented foods, e.g. wine, dry sausage, sauerkraut, miso, and soy sauce. See our FAQ on Histamine in Foods other than Fish and Fishery products.

 What are the symptoms of illness? 
Onset of symptoms of histamine food poisoning can range from several minutes to several hours following ingestion of toxin. Typically, the average incubation period before onset of illness is approximately one hour. Severity of illness varies, depending on factors such as the level of exposure and the susceptibility of the affected individual. Typically observed symptoms are:

  • Nausea
  • Malaise
  • Vomiting
  • Diarrhoea
  • Abdominal cramps
  • Headaches
  • Skin rash
  • Flushing
  • Burning sensation of the mouth and lips
  • A peppery taste sensation
  • Hives
  • Itching
  • Hypotension

How is histamine produced? 
Histamine is produced when bacteria that naturally occur in the skin, gills and gut of fish break down histidine, an amino acid found in the muscles of certain fish species that contain naturally high levels of this amino acid (mackerel/herring/sardines/tuna). The production of histamine is directly related to the mishandling of food as a result of storage at incorrect temperatures. Histidine decarboxylase, the enzyme responsible for breaking down histidine into histamine, can remain active even after the bacteria responsible for producing it have been inactivated or killed. The enzyme continues histamine production slowly at refrigeration temperatures and remains stable if frozen, thus allowing it to rapidly recommence activity after thawing. Although the enzyme that produces histamine can be inactivated by cooking, once histamine has been produced, it cannot be eliminated by normal cooking or freezing temperatures, and its toxicity remains intact.

 What are the signs of food spoilage that can result in high levels of histamine? 
Harmful levels of histamine can build up in fish before any signs of spoilage develop, such as a bad smell or taste. For these reasons, control strategies focus on prevention through the use of strict temperature control throughout the food chain.

 Which bacteria are involved? 
A wide range of bacteria are capable of producing histamine. Examples include Morganella morganii, Klebsiella spp., Pseudomonas, Clostridium, Citrobacter freundii and more. Many of these bacteria are found naturally in fish environments.

How is histamine controlled?  
Strict control of the cold chain is essential to prevent the formation of histamine. Fish must be chilled immediately after catching, as this is the highest risk period for bacterial growth and histamine production. The integrity of the cold chain must be protected throughout all processing stages (catching/transport/delivery/sale) in order to control histamine production and ensure maximum product shelf life. Records of cold chain integrity should be kept at all stages of the food chain.

A food business operator should:

  • Store fish frozen or at 0 °C (on ice) as per the requirements in Regulation 853/2004 (as amended)
  • Examine supplier temperature records to ensure fish was rapidly chilled after catching
  • Examine supplier records to ensure that a temperature approaching that of melting ice were maintained throughout storage and transport
  • Ensure that fish is stored immediately on receipt and that temperatures of 0 °C (on ice) are maintained at all times
  • Keep records of all temperatures throughout the food chain to ensure compliance 
  • Take account of relevant information accompanying incoming product such as date of minimum durability, date of freezing or first freezing (unprocessed fishery products), date of production and date of freezing if different from date of production (frozen products of animal origin) 
  • Assign an appropriate shelf life.

Can processing technologies prevent histamine production? 
Bacteria associated with histamine production are readily found in salt water. As such, many of these bacteria are halotolerant (salt resistant) or halophilic (salt loving) and some are capable of producing histamine under acidic conditions (low pH). Therefore, histamine production is possible even during processes such as smoking, brining, salting, fermenting and drying. Histamine already produced can also survive these processes. In addition, vacuum packaging is not an effective method of preventing the production of histamine.

What histamine levels are harmful in foods? 
Levels of above 200 mg/kg (ppm) have been associated with human illness. However, levels as low as 50 mg/kg have known to cause illness, but this is uncommon. Most cases of illness caused by histamine in fish have been above 200 mg/kg, and often above 500 mg/kg.

What are the legal limits for histamine in food? 
Commission Regulation (EC) No 2073/2005 on microbiological criteria for foodstuffs (as amended) lays down standards for fishery products which are associated with high levels of histamine. If a product exceeds the legal limits laid down in the Regulation, then a withdrawal or recall of the product or batch of foodstuff from the market should be issued in accordance with Article 19 of Regulation (EC) No 178/2002.

See FAQ on histamine in foods other than fish and fishery products.

Table 1 Legal limits for histamine in fishery products placed on the market during their shelf life outlined in Commission Regulation 2073/2005 (as amended)

Food category

Sampling plan(1)

Histamine limits

Analytical reference method

Stage where criterion applies

n

c

m

M

1.26 Fishery products from fish species associated with a high amount of histidine(17)

9(18)

2

100 mg/kg

200 mg/kg

HPLC(19)

Products placed on the market during their shelf life

1.27 Fishery products, except those in food category 1.27a, which have undergone enzyme maturation treatment in brine, manufactured from fish species associated with a high amount of histidine(17)

9(18)

2

200 mg/kg

400 mg/kg

HPLC(19)

Products placed on the market during their shelf life

1.27a Fish sauce produced by fermentation of fishery products

1

0

400 mg/kg

HPLC(19)

Products placed on the market during their shelf life


1n = number of units comprising the sample; c = number of sample units giving values between m and M, where m is the lower limit and M is the upper limit.
17Particularly fish species of the families: Scombridae, Clupeidae, Engraulidae, Coryenidae, Pomatomidae, Scombresosidae.
18 Single samples may be taken at retail level. In such cases, the presumption laid down in Article 14(6) of Regulation (EC) No 178/2002, according to which the whole batch should be deemed unsafe, shall not apply, unless the result is above M.
19References: 1. Malle P., Valle M., Bouquelet S. Assay of biogenic amines involved in fish decomposition. J. AOAC Internat 1996, 79, 43-49. 2. Duflos G., Dervin C., Malle P., Bouquelet S. Relevance of matrix effect in determination of biogenic amines in plaice (Pleuronectes platessa) and whiting (Merlangus merlangus). J. AOAC Internat 1999, 82, 1097–1101


Therefore, using Food category 1.26 as an example for interpretation of results: 

  • A batch would be designated Satisfactory if 9 sample units were taken (n=9) and all 9 units were below 100 mg/kg
  • A batch would be designated Acceptable if 9 sample units (n=9) were taken and a maximum of 2 (e.g. c=1 or 2) of those units were between 100 mg/kg and 200 mg/kg
  • A batch would be designated Unsatisfactory if:
    • 9 sample units (n=9) were taken and more than 2 (e.g. c=3) of those units were between 100 mg/kg and 200 mg/kg
    • Any (n=1) of the 9 total sample units (n=9) exceeds the maximum upper limit M of 200 mg/kg.
     

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Last reviewed: 2/7/2018

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